Snap action control device



July 12, 1949. v. WEBER ETAL 2,476,230

SNAP-ACTION CONTROL DEVICE Filed March 14, 1947 gwwa/wtowf vzcroe mess wjLLm/v s. KUNZL ER.

the/r Patented July 12, 1949 SNAP ACTION CONTROL DEVICE Victor Weber and William S. Kunzler, Greensburg, Pa., assignors to Robertshaw-Fulton Controls Company, a corporation of Delaware Application March 14, 1947, Serial No. 734,616

8 Claims. 1

This invention relates to snap-action control devices and, more particularly, to latched lever mechanisms adapted to be tripped to produce the snap-action.

An object of the invention is to simplify the latch trip mechanism of the control device for installation in a confined space.

Another object of the invention is to avoid reduction of the capacity of the control device while rendering the mechanism more compact.

Another object of the invention is to facilitate assembly and ensure economy in manufacture of the control device.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawing, wherein:

Fig. 1 is a longitudinal sectional view of the control device of thisinvention;

Fig. 2 is a cross section taken on the line 11-11 of Fig. l; and

Fig. 3 is a schematic view of certain essential portions of the control device in latched position.

Referring more particularly to the drawing, the snap-action mechanism is housed within a casing it] provided with a detachable front cover l2 and a mounting bracket M on the rear wall thereof. The upper end of the casing ii! is open and an insulating block l6 securedto the rear wall of the casing i provides a partial closure therefor. Adjacent the front cover i2 the insulating block l6 carries a pair of spaced terminals i8 from which a pair of contact means 26 depend into the interior of the casing iii.

The contact means 2t) are relatively stationary and are insulated from the front cover i2 by an insulating liner 22 for the front cover i2. Relatively movable contact means in the form of a contact bar 24 is cooperable with the contact means for opening and closing a circuit connected to the terminals i8. The contact bar 24 is loosely mounted on an insulating strip 25 which is rigidly connected to a control lever 28.

The control lever 28 is provided with a pair of ears 30 extending one from each side thereof toward the rear wall of the casing iii. The ears 30 are spaced from the side walls of the casing l0 and are apertured to receive pin means 32 projecting from the side walls and by which the control lever 28 is pivoted intermediate its ends. The end of the lever 28 adjacent the lower wall of the casing In is provided with a rearward angularly bent portion 34 for a purpose apparent hereinafter.

Operating means are provided for opening the contact means 20, 24 by operative engagement with the control lever 28. The operating means consists of a plate 40 positioned between the control lever 28 and the front cover i2 and having a pair of ears 42 extending between the cars 30 of the control lever and the side walls of the casing ill. The pin means 32 extend through suitable apertures in the cars 42 to provide a common pivot for the control lever 28 and the operating means 40. One of the ears 42 is also extended rearwardly to form an inturned bent portion 44 provided with a notch 46. An operating finger 41 projects from the plate 40 for operative engagement with the control lever 28 when the parts are suitably positioned.

A second lever 48 is positioned on the opposite side of the control lever 28 to the operating means 40 and is provided with a pair of ears 58 suitably apertured to accommodate pin means 52 projecting from the side walls of the casing ii) and upon which the second lever 48 is pivoted at one end thereof. The second lever 48 extends substantially parallel with the control lever 28 which is cut-away at one side to accommodate yieldable means in the form of a coil spring 56 mounted for operative engagement with the operating means 40 and the second lever 48, respectively. This arrangement of the yieldable means or coil spring 54 serves to bias the operating means Mi and the second lever 48 apart. A second biasing means in the form of a coil spring 55 is mounted to operatively engage the operating means 40 and the control lever 28 at the location of the bent portion 34 which serves to accommodate this second biasing means. The coil spring 58 serves to bias the control lever 28 to maintain the contact means 20, 24 closed.

Latching means are operatively associated with the second lever 48 and the operating means 46 and are effective for preventing movement of the operating means 40 into operative relation with the control lever 28 such as would cause the operating finger 41 to operatively engage the control lever 28 for moving the same. To this end, a portion of the second lever 48 is bent rearwardly as at 58 and provided with a notch 60 which is adapted to be engaged by the notch 46 formed on the inturned portion 44 of the operating means 48.

Condition responsive means for the control device are shown as comprising an actuating element 62 provided with a stud 64 'by which it is secured to the rear wall of the casing ii! on the interior thereof with the usual capillary tube 88 and bulb element (not shown) positioned exterior of the casing l0. The condition responsive means is filled with a suitable liquid which will expand upon temperature changes sensed by the bulb element or upon changes in pressure where a pressure responsive device is employed. Expansion of the actuating element 62 serves to move a button 68 carried bythe actuating element 62 into operative engagement with an adjustment screw 10 which projects from the second lever 48 intermediate the pivot 52 and the latching means 46, 60.

When the actuatingelement 82 has operated the device to open the contacts 20, 24, then manual resetting means are employed to return the control lever 28 to its original position. This means comprises a reset button 12 which is reciprocable in a bearing 14 provided in the front cover 12 and which is operatively engageable with the operating means fill for rotating it on its pivot formed by the pin means 32.

In the operation of the device it may be assumed that the temperature or pressure to which the actuating element 62 is responsive is at a predetermined low value and that the actuating element 62 is in its contracted position, as indicated in Fig. 3. Thus, the latching means comprising the notches 46 and 60 on the operating means 40 and the'second lever 48. respectively, are in engagement and the contacts 2d, 2 are closed. As the actuating element 82 expands in response to an increase in temperature or pressure, the second lever 48 is moved in a clockwise direction as viewed in Fig. 3 by the button 68 against the bias of the spring 54. Due to the latching engagement of the second lever d8 therewith, there is no movement of the operating means 40 at this time so that the spring is compressed. Consequently, the operating means 40 is held in its initial position for a limited period which is terminated upon tripping of the latching means due to disengagement of the notches 46, 60 when the movement of the lever 48 has proceeded far enough. It may be noted that the spring 56 tends to turn the control lever 28 counterclockwise and that the contacts 20, 24 remain closed while the operating means dd is held in its initial position.-

- Upon tripping of the latching means by disengagement of notches 46, 60 the stored energy in the coil spring 54 is suddenly released and the operating finger 41 contacts the control lever 28 with sufiicient force to open the contacts 20, 24 with snap action. It will be apparent that the snap-action movement of the control lever 40 which also moves in a clockwise direction upon tripping of the latching means.

The contacts 20, 24 remain open and can only be reset to closed position after the actuating element 82 has contracted in response to a decrease in the temperature or pressure to which it responds. The reset button 12 can then be operated manually to move the operating means 40 in a clockwise direction about the pivot formed by pin means 32 to latch the latching means by reengaging notches 46, 60 and restore the control lever 28' to its original position. v

The control device can be calibrated by adjustment of the screw 10. In the device shown and described herein the setting is fixed as will be apparent. However, it will be understood that the adjustment screw could beextended to the exterior of the cover l2 to make the control device adjustable if desired. Due to the absence of mechanical linkage and reliance upon the springs 54 and 58 the control is rendered simple to manufacture and assemble. While a preferred embodiment of the invention is shown and described herein, it will be understood that many changes may be made in the combination and arrangement of parts and in the details of construction within the scope of the appended claims without departing from the invention disclosed herein.

We claim:

1. A control device comprising in combination, a pivoted lever movable between controlling positions, means for biasing said lever to one of said positions, operating means movable from an initial position into operative engagement with said lever for exerting a force thereon suffioient to overcome said biasing means, a second pivoted lever movable relative to said operating means, yieldable means operative for biasing said operating means and said second lever apart, and latching means for holding said operating means in said initial position for a limited period during which said second lever is movable against the bias of said yieldable means, said limited period being terminated upon tripping of said latching means to cause snap-action movement of said operating means from said initial position by said yieldable means.

2. A control device comprising in combination, a pivoted lever movable between controlling positions, means for biasing said lever to one of said positions, operating means movable from an initial position into operative engagement with said lever for exerting a force thereon suflicient to overcome said biasing means,'a second pivoted lever movable relative to said operating means, yieldable means operative for biasing said operating means and said second lever apart, and latching means operative between said operating means and said second lever for holding said operating means in said initial position for a limited period during which said second lever is movable against the bias of said yieldable means, said limited period being terminated upon tripping of said latching means to cause snap-action movement of said operating means from said initial position by said yieldable means.

3. A control device comprising in combination, a pivoted lever movable between controlling positions, means for biasing said lever to one of said positions, operating means movable from an initial position into operative engagement with said lever for exerting a force thereon suflicient to overcome said biasing means, a second pivoted lever movable relative to said operating means, yieldable means operative for biasing said operating means and said second lever apart, and latching means operatively associated with said operating means and said second lever for holding said operating means in said initial position, said latching means being adapted to be tripped after a relative movement of said operating means and said second lever has occurred against the bias of said yieldable means thereby causing snapaction movement of said operating means from said initial position by said yieldable means.

4. A control device comprising in combination, a control lever pivoted intermediate its ends for movement between controlling positions, means operatively engageable with one end of said lever for biasing said lever to one of said positions, operating means positioned on one side of said lever and movable from an initial position into operative engagement therewith for exerting a :2,47e,eso

force thereon sumclent to overcome said biasing means, a second lever pivoted at one end thereof and extending substantially parallel with said control lever on the opposite side thereof to said operating means, yieldable means operative for biasing said operating means and said second iever apart, and latching means operatively associated with said operating means and said second iever for holding said operating means in said initial position, said latching means being adapted to ice-tripped after a relative movement of said operating means and said second lever has occurred against the bias of said yieldable means thereby causing snap-action movement of said operating means from said initial position by said yieldable means.

55. A control device comprising in combination, a control lever pivoted intermediate its ends for movement between controlling positions, contact means cooperable with said lever, means operatively engageable with one end of said lever for biasing said lever to close said contact means, operating means positioned on one side oi said iever and movable from an initial position into operative engagement with the opposite end of said lever for opening said contact means, a secand lever pivoted at one end thereof and extending substantially parallel with said control lever on the opposite side thereof to said operating means, yieidable means operative for biasing said operating means and said second lever apart, latching means for holding said operating means in said initial position for a limited period during which said second lever is movable against the bias of said yieldable means, said'limited period being terminated upon tripping of said latching means to cause snap-action movement of said operating means from said initial position by said yieldable means, and means operatively engageable with said operating means for returning said control lever to its original position..

6. A snap-action device comprising in combination, a control lever, pivoted operating means movable into operative relation with said control lever, means for biasing said operating means toward said control, lever, a second lever, latching means operativcly associated with said second lever and said operating means and effective for preventing said movement of the operating means, biasing means for urging said second lever and said operating means: apart, and condition responsive means for compressing said biasing means while said latching means is eflective and thereafter causing release or said operating means with snap-action.

7. A snap-action device comprising in combination, a control lever pivoted intermediate its ends,

operating means pivotally mounted for movement into operative relation with said control lever, means for biasing said operating means toward said control lever, a second lever pivoted adjacent one end and extending substantially parallel with said control lever, latching means operatively associated with said second lever and said operating means and eii'ective ior preventing said movement of the operating means, a coil spring Y iorbiasing said second lever and said operating means apart, and condition responsive means for compressing said spring while said latching means is reflective and thereafter causing release of said operating means with snap-action.

ii. A snap-action device comprising in combina tion, a control lever pivoted intermediate its-ends, contact means mounted upon one end of said iever, relativelystationars contact means cooperable with the first said contact means, operating means pivotally mounted for movement into operative relation with said control lever, means ior biasing said operating means toward said control lever and said first contact means toward said stationary contact means, asecond lever pivoted adjacent one end and extending substantially parallel with said control lever, latching means operatively associated with said second lever and said operating means and eflective for preventing said movement of the operating means, a coil spring for biasing said second lever and said operating means apart, condition responsive means for compressing said spring while said latching means is eflective and thereafter causing release of said operating means with snap-action to move said first contact means away from said stationary contact means, and manually operable means engageable with said operating means for returning said control lever to its original position.

VICTOR WEBER. WILLIAM S. 'KUNZLER.

REFERENCES CITED The following references are or record in the tile or this patent:

um'rrro s'rs'rssPA-rsn'rs Name a 1,287,491 Bpaulding Dec. 10, 1918 

